Contradictory views exist regarding whether business?information technology (IT) alignment enhances or reduces organizational agility, and no consensus has been achieved. To disentangle this puzzle, this study takes both the intellectual and social dimensions of IT alignment into account and investigates how they influence agility in opposite directions through distinct mechanisms. Based on survey data from 429 dyads of business and IT executives, we uncover that intellectual alignment impedes agility by increasing organizational inertia, while social alignment facilitates agility by enhancing emergent business?IT coordination. We also find that social alignment weakens the effect of intellectual alignment on organizational inertia. This paper fills a gap in the information systems (IS) literature by providing a theory-driven explanation of the alignment paradox, which makes a significant contribution to both IS research and practice.